Many weapons and firearms use magazines to provide access to multiple cartridges without the need to reload the weapons or firearms. Different magazines can hold different numbers of cartridges. Further, some weapons can support different size magazines.
It is often beneficial for a user to know how much ammunition is available to the user. For example, when hunting or in a firefight, it is important for the user to know whether the user has sufficient ammunition. This can often be determined by the user when loading a magazine as the user can count how many cartridges are placed in the magazine. However, when the user is in a situation where he or she is firing a weapon, the user may easily lose track of the amount of ammunition fired and/or remaining.